Novel polymers and photoresist compositions comprising same

ABSTRACT

The invention includes polymers that contain a polymers of the invention contain one or more 1) carbonate units and/or 2) a lactone provided by a monomer having a ring oxygen adjacent to the monomer vinyl group. The invention also provides photoresists that contain such polymers, particularly for imaging at short wavelengths such as sub-200 nm.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to new polymers that contain unitsof fused carbonate groups and/or a lactone provided by a monomer havinga ring oxygen adjacent to the monomer vinyl group. Polymers of theinvention are highly useful as a resin component for photoresistcompositions, particularly chemically-amplified positive-acting resiststhat can be effectively imaged at short wavelengths such as sub-200 nm,particularly 193 nm.

[0003] 2. Background

[0004] Photoresists are photosensitive films used for transfer of imagesto a substrate. A coating layer of a photoresist is formed on asubstrate and the photoresist layer is then exposed through a photomaskto a source of activating radiation. The photomask has areas that areopaque to activating radiation and other areas that are transparent toactivating radiation. Exposure to activating radiation provides aphotoinduced chemical transformation of the photoresist coating tothereby transfer the pattern of the photomask to the photoresist-coatedsubstrate. Following exposure, the photoresist is developed to provide arelief image that permits selective processing of a substrate.

[0005] A photoresist can be either positive-acting or negative-acting.For most negative-acting photoresists, those coating layer portions thatare exposed to activating radiation polymerize or crosslink in areaction between a photoactive compound and polymerizable reagents ofthe photoresist composition. Consequently, the exposed coating portionsare rendered less soluble in a developer solution than unexposedportions. For a positive-acting photoresist, exposed portions arerendered more soluble in a developer solution while areas not exposedremain comparatively less developer soluble. Photoresist compositionsare described in Deforest, Photoresist Materials and Processes, McGrawHill Book Company, New York, ch. 2, 1975 and by Moreau, SemiconductorLithography, Principles, Practices and Materials, Plenum Press, NewYork, ch. 2 and 4.

[0006] More recently, chemically-amplified-type resists have beenincreasingly employed, particularly for formation of sub-micron imagesand other high performance applications. Such photoresists may benegative-acting or positive-acting and generally include manycrosslinking events (in the case of a negative-acting resist) ordeprotection reactions (in the case of a positive-acting resist) perunit of photogenerated acid. In the case of positivechemically-amplified resists, certain cationic photoinitiators have beenused to induce cleavage of certain “blocking” groups pendant from aphotoresist binder, or cleavage of certain groups that comprise aphotoresist binder backbone. See, for example, U.S. Pat. Nos. 5,075,199;4,968,581; 4,883,740; 4,810,613; and 4,491,628, and Canadian PatentApplication 2,001,384. Upon cleavage of the blocking group throughexposure of a coating layer of such a resist, a polar functional groupis formed, e.g., carboxyl or imide, which results in differentsolubility characteristics in exposed and unexposed areas of the resistcoating layer. See also R. D. Allen et al., Proceedings of SPIE,2724:334-343 (1996); and P. Trefonas et al. Proceedings of the 11thInternational Conference on Photopolymers (Soc. Of Plastics Engineers),pp 44-58 (Oct. 6, 1997).

[0007] While currently available photoresists are suitable for manyapplications, current resists also can exhibit significant shortcomings,particularly in high performance applications such as formation ofhighly resolved sub-half micron and sub-quarter micron features.

[0008] Consequently, interest has increased in photoresists that can bephotoimaged with short wavelength radiation, including exposureradiation of about 250 nm or less, or even about 200 nm or less, such aswavelengths of about 248 nm (provided by KrF laser) or 193 nm (providedby an ArF exposure tool). See European Published Application EP915382A2.Use of such short exposure wavelengths can enable formation of smallerfeatures. Accordingly, a photoresist that yields well-resolved imagesupon 248 nm or 193 nm exposure could enable formation of extremely small(e.g. sub-0.25 μm) features that respond to constant industry demandsfor smaller dimension circuit patterns, e.g. to provide greater circuitdensity and enhanced device performance.

[0009] However, many current photoresists are generally designed forimaging at relatively higher wavelengths, such as G-line (436 nm) andI-line (365 nm) are generally unsuitable for imaging at shortwavelengths such as sub-200 nm. Even shorter wavelength resists, such asthose effective at 248 nm exposures, also are generally unsuitable forsub-200 nm exposures, such as 193 nm imaging.

[0010] More specifically, current photoresists can be highly opaque toextremely short exposure wavelengths such as 193 nm, thereby resultingin poorly resolved images.

[0011] It thus would be desirable to have new photoresist compositions,particularly resist compositions that can be imaged at short wavelengthssuch as sub-200 nm exposure wavelengths, particularly 193 nm.

SUMMARY OF THE INVENTION

[0012] We have now found novel polymers and photoresist compositionsthat comprise the polymers as a resin binder component. The photoresistcompositions of the invention can provide highly resolved relief imagesupon exposure to extremely short wavelengths, particularly sub-200 nmwavelengths such as 193 nm.

[0013] Polymers of the invention contain one or more 1) carbonate units(such as provided by reaction of a vinyl carbonate e.g. vinylenecarbonate) and/or 2) a lactone provided by a monomer having a ringoxygen adjacent to the monomer vinyl group such as α-angelicalactone andγ-methylene-γ-butyrolactone.

[0014] Polymers of the invention also may contain an oxygen- and/orsulfur-containing heteroalicyclic ring that is preferably fused to thepolymer backbone (i.e. at least two heteroalicyclic ring atoms as partof the polymer backbone). The heteroalicyclic ring has one or moreoxygen and/or sulfur atoms as ring members.

[0015] Preferred polymers of the invention also may contain a carbonalicyclic group (i.e. the group has all carbon ring members) that isfused to the polymer backbone, i.e. the carbon alicyclic ring has atleast two carbon ring members that comprise the polymer backbone.Preferred fused carbon alicyclic groups are provided by polymerizationof cyclic olefin (endocyclic double bond) compounds such as optionallysubstituted norbomene groups.

[0016] Preferred heteroalicyclic polymer units may be substituted, e.g.by heteroalkyl groups such as ethers (alkoxy) preferably having 1 toabout 10 carbon atoms, alkylthio preferably having 1 to about 10 carbonatoms, alkylsulfinyl preferably 1 to about 10 carbon atoms,alkylsulfonyl preferably having 1 to about 10 carbon atoms, and thelike. It has been surprising found that such substituents can provideenhanced lithographic results, particularly enhanced substrate adhesion.

[0017] For use in photoresist compositions, polymers of the inventionalso will contain one or more units that comprise photoacid-labilemoieties. The photoacid-labile group may be a substituent of one or moreof the above-mentioned units, such as a substituent of a polymerizedvinyl alicyclic ether, vinyl alicyclic thioether or carbon alicyclicgroup. The photoacid labile moiety also may be present as an additionalpolymer unit, e.g. as a polymerized alkyl acrylate or alkylmethacrylate,particularly an acrylate having an alicyclic moiety such asmethyladamantyl acrylate or methyladamantyl metacrylate. Preferredalicyclic photoacid-labile moieties are tertiary ester alicyclichydrocarbon groups that have two or more fused or bridged rings.Preferred tertiary ester groups include optionally substitutedadamantyl, particularly methyl adamantyl as mentioned above; optionallysubstituted fencyl groups, particularly ethyl fencyl; optionallysubstituted pinanyl; and optionally substituted tricyclo decanyl,particularly an alkyl-substituted tricyclo decanyl such as8-ethyl-8-tricyclodecanyl e.g. as provided by polymerization of8-ethyl-8-tricyclodecanyl acrylate and 8-ethyl-8-tricyclodecanylmethacrylate. Additional alicyclic ester groups also will be suitable,including additional bicyclic, tricyclic and other polycyclic moieties.

[0018] Polymers of the invention also may contain units in addition tothe above groups. For example, polymers of the invention also maycontain nitrile units such as provided by polymerization ofmethacrylonitrile and acrylonitrile. Additional contrast enhancinggroups also may be present in polymers of the invention, such as groupsprovided by polymermization of methacrylic acid, acrylic acid, and suchacids protected as photoacid labile esters, e.g. as provided by reactionof ethoxyethyl methacrylate, t-butoxy methacrylate, t-butylmethacrylateand the like.

[0019] Generally preferred polymers of the invention contain 3, 4 or 5distinct repeat units, i.e. preferred are terpolymers, tetrapolymers andpentapolymers that contain one or more heteroalicyclic groups asdisclosed herein.

[0020] Particularly preferred polymers of the invention include:

[0021] 1) a polymer that contains distinct repeat units of i) acarbonate and/or lactone as discussed above; ii) maleic anhydride; andiii) an acrylate or methacrylate including those that contain aphotoacid-labile group such as t-butylacrylate, adamantylacrylate andthe like;

[0022] 2) a polymer that contains distinct repeat units of i) acarbonate and/or lactone as discussed above; ii) maleic anhydride; andiii) a vinyl alicyclic, including carbon alicyclics and heteroalicyclicsas discussed above;

[0023] 3) a polymer that contains distinct repeat units of i) acarbonate and/or lactone as discussed above; ii) maelic anhydride; andiii) a vinyl alicyclic, including carbon alicyclics and heteroalicyclicsas discussed above; and

[0024] .4) a polymer that contains distinct repeat units of i) acarbonate and/or lactone as discussed above; ii) maleic anhydride; iii)a vinyl alicyclic, including carbon alicyclics and heteroalicyclics asdiscussed above; and iv) an acrylate or methacrylate including thosethat contain a photoacid-labile group such as t-butylacrylate,adamantylacrylate and the like.

[0025] Polymers of the invention are preferably employed in photoresistsimaged at 193 run, and thus preferably will be substantially free of anyphenyl or other aromatic groups. For example, preferred polymers containless than about 5 mole percent aromatic groups, more preferably lessthan about 1 or 2 mole percent aromatic groups, more preferably lessthan about 0.1, 0.02, 0.04 and 0.08 mole percent aromatic groups andstill more preferably less than about 0.01 mole percent aromatic groups.Particularly preferred polymers are completely free of aromatic groups.Aromatic groups can be highly absorbing of sub-200 nm radiation and thusare undesirable for polymers used in photoresists imaged with such shortwavelength radiation.

[0026] Polymers of the invention also may be suitably employed inresists used for imaging at other wavelengths such as sub-300 nm andsub-170 nm, particularly 2248 nm and 157 nm. Polymers employed inresists imaged at 248 nm suitably may contain aromatic groups, includingphenyl groups particularly phenolic gropups as may be provided byreaction of the corresponding vinyl monomer (e.g. vinylphenol). Polymersemployed in resists imaged at 157 nm suitably have halogen substitution,particularly fluorine substitution such as may be provided byco-polymerization of a fluoro-olefin, e.g. tetrafluoroethylene.

[0027] The invention also provides methods for forming relief images,including methods for forming a highly resolved relief image such as apattern of lines where each line has essentially vertical sidewalls anda line width of about 0.40 microns or less, and even a width of about0.25, 0.20 or 0.16 microns or less. The invention further providesarticles of manufacture comprising substrates such as a microelectronicwafer substrate or liquid crystal display or other flat panel displaysubstrate having coated thereon a polymer, photoresist or resist reliefimage of the invention. Other aspects of the invention are disclosedinfra.

DETAILED DESCRIPTION OF THE INVENTION

[0028] As discussed above, polymers of the invention contain one ormore 1) carbonate units and/or 2) a lactone provided by a monomer havinga ring oxygen adjacent to the monomer vinyl group.

[0029] Exemplary monomers that may be employed to provide such monomersinclude the following:

[0030] As also discussed above, polymers of the invention may containother units. Preferred polymers of the invention may contain additional(i.e. distinct from the carbonate and/or lactone) heteroalicyclic ringsthat are preferably fused to a polymer backbone. The fused heterocyclicring. units contain one or more oxygen and/or sulfur atoms. By statingherein that a cyclic group is fused to a polymer backbone, it is meantthat two ring members of the cyclic group, typically two adjacent carbonatoms of the cyclic group, are also part of the polymer backbone. Such afused ring can be provided by polymerizing a cyclic monomer that has anendocyclic double bond.

[0031] Additional preferred polymer units are polymerized carbonalicyclic compounds such as optionally substituted norbornene. Asreferred to herein, the term “carbon alicyclic group” means each ringmember of the non-aromatic group is carbon. The carbon alicyclic groupcan have one or more endocyclic carbon-carbon double bonds, provided thering is not aromatic.

[0032] Preferred polymers of the invention will contain at least about 2to 5 mole percent of fused heteroalicyclic units based on total units ofthe polymer; more preferably from about 5 to 50 mole percent of fusedheteroalicyclic units based on total units of the polymer; still morepreferably from about 5 or 10 to about 40 or 50 percent of fusedheteroalicyclic units based on total units of the polymer.

[0033] Preferred polymers of the invention will contain at least about 2to 5 mole percent of carbon alicyclic units based on total units of thepolymer; more preferably from about 5 to 50 mole percent of fused carbonalicyclic units based on total units of the polymer; still morepreferably from about 5 or 10 to about 25 or 30 percent of fused carbonalicyclic units based on total units of the polymer.

[0034] In polymers of the invention that contain only heteroalicyclicunits and carbon alicyclic units, preferably the heterocyclic units willbe present in an amount of from about 5 to about 90 or 95 mole percentbased on total polymer units, and the carbon alicyclic units will bepresent in an amount of from about 5 to about 90 or 95 mole percentbased on total polymer units.

[0035] In polymers of the invention that consist of heteroalicyclicunits, carbon alicyclic units and maleic anhydride units (i.e. carbonateor lactone:carbon alicyclic:maleic anhydride terpolymers), preferablythe carbonate and/or lactone units will be present in an amount of fromabout 5 to about 10, 20, 30, 40, 50, 60, 70 or 80 mole percent based ontotal polymer units, the carbon alicyclic units (such as optionallysubstituted norbomene) will be present in an amount of from about 5 toabout 10, 20, 30, 40, 50, 60, 70 or 80 mole percent based on totalpolymer units, and the maleic anhydride units will be present from about5 to about 20, 30, 40 or 50 mole percent based on total polymer units;and more preferably the carbonate and/or lactone units will be presentin an amount of from about 5 to about 10, 20, 30, 40, 50 or 60 molepercent based on total polymer units, the carbon alicyclic units will bepresent in an amount of from about 5 to about 10, 20, 30, 40, 50 or 60mole percent based on total polymer units, and the maleic anhydrideunits will be present from about 5 to about 10, 15, 20, 25, 30, 40, or50 mole percent based on total polymer units. In such terpolymers,suitably the carbon alicyclic units will contain a photo acid labilesubstituents such as a photoacid-labile ester substituent.

[0036] In any event, polymers of the invention preferably comprisecontain one or more repeat units that comprise a photoacid-labile group.The photoacid-labile may be suitably a substituent of a carbon alicyclicring member (norbomene) or, alternatively and generally preferred, thephotoacid-labile moiety will be a polymer repeat unit distinct fromrepeat units containing an alicyclic group and may be e.g. a polymerizedacrylate or methacrylate group.

[0037] Preferred photoacid-labile groups are ester groups, particularlyesters that contain a tertiary alicyclic hydrocarbon ester moiety.Preferred tertiary alicyclic hydrocarbon ester moieties are polycyclicgroups such adamantyl, ethylfencyl or a tricyclo decanyl moiety.References herein to a “tertiary alicyclic ester group” or other similarterm indicate that a tertiary alicyclic ring carbon is covalently linkedto the ester oxygen, i.e. —C(═O)O-TR′ where T is a tertiary ring carbonof alicyclic group R′. In at least many cases, preferably a tertiaryring carbon of the alicyclic moiety will be covalently linked to theester oxygen, such as exemplified by the below-depicted specificallypreferred polymers. However, the tertiary carbon linked to the esteroxygen also can be exocyclic to the alicyclic ring, typically where thealicyclic ring is one of the substituents of the exocyclic tertiarycarbon. Typically, the tertiary carbon linked to the ester oxygen willbe substituted by the alicyclic ring itself, and/or one, two or threealkyl groups having 1 to about 12 carbons, more typically 1 to about 8carbons, even more typically 1, 2, 3 or 4 carbons. The alicyclic groupalso preferably will not contain aromatic substitution. The alicyclicgroups may be suitably monocyclic, or polycyclic, particularly bicyclicor tricyclic groups.

[0038] Preferred alicyclic moieties (e.g. group TR′ of —C(═O)O-TR′) ofphotoacid labile ester groups of polymers of the invention have ratherlarge volume. It has been found that such bulky alicyclic groups canprovide enhanced resolution when used in copolymers of the invention.

[0039] More particularly, preferred alicyclic groups of photoacid labileester groups will have a molecular volume of at least about 125 or about130 Å³, more preferably a molecular volume of at least about 135, 140,150, 155, 160, 165, 170, 175, 180, 185, 190, 195, or 200 Å³. Alicyclicgroups larger than about 220 or 250 Å³ may be less preferred, in atleast some applications. References herein to molecular volumesdesignate volumetric size as determined by standard computer modeling,which provides optimized chemical bond lengths and angles. A preferredcomputer program for determining molecular volume as referred to hereinis Alchemy 2000, available from Tripos. For a further discussion ofcomputer-based determination of molecular size, see T Omote et al,Polymers for Advanced Technologies, volume 4, pp. 277-287.

[0040] Particularly preferred tertiary alicyclic groups ofphotoacid-labile units include the following, where the wavy linedepicts a bond to the carboxyl oxygen of the ester group, and R issuitably optionally substituted alkyl, particularly C₁₋₈ alkyl such asmethyl, ethyl, etc.

[0041] Polymers of the invention also may contain photoacid-labilegroups that do not contain an alicyclic moiety. For example, polymers ofthe invention may contain photoacid-labile ester units, such as aphotoacid-labile alkyl ester. Generally, the carboxyl oxygen (i.e. thecarboxyl oxygen as underlined as follows: —C(═O)O) of thephotoacid-labile ester will be covalently linked to the quaternarycarbon. Branched photoacid-labile esters are generally preferred such ast-butyl and —C(CH₃)₂CH(CH₃)_(2.)

[0042] Polymers of the invention also may contain additional units suchas cyano units, lactone units or anhydride units. For example,acrylonitrile or methacrylonitrile may be polymerized to provide pendantcyano groups, or maleic anhydride may be polymerized to provide a fusedanhydride unit.

[0043] As discussed above, polymers of the invention are preferablyemployed in photoresists imaged at short wavelengths, particularlysub-200 nm such as 193 nm and 157 nm. Polymers also can be employed inphotoresists imaged at higher wavelengths such as 248 nm. For suchhigher wavelength applications, the polymer may suitably containaromatic units, e.g. polymerized styrene or hydrostyrene units.

[0044] Polymers of the invention can be prepared by a variety ofmethods. One suitable method is an addition reaction which may includefree radical polymerization, e.g., by reaction of selected monomers toprovide the various units as discussed above in the presence of aradical initiator under an inert atmosphere (e.g., N₂ or argon) and atelevated temperatures such as about 70° C. or greater, although reactiontemperatures may vary depending on the reactivity of the particularreagents employed and the boiling point of the reaction solvent (if asolvent is employed). Suitable reaction solvents include e.g.tetrahydrofuran, ethyl lactate and the like. Suitable reactiontemperatures for any particular system can be readily determinedempirically by those skilled in the art based on the present disclosure.A variety of free radical initiators may be employed. For example, azocompounds may be employed such as azo-bis-2,4-dimethylpentanenitrile.Peroxides, peresters, peracids and persulfates also could be employed.

[0045] Other monomers that can be reacted to provide a polymer of theinvention can be identified by those skilled in the art. For example, toprovide photoacid-labile units, suitable monomers include e.g.methacrylate or acrylate that contains the appropriate groupsubstitution (e.g. tertiary alicyclic, t-butyl, etc.) on the carboxyoxygen of the ester group. Maleic anhydride is a preferred reagent toprovide fused anhydride polymer units. Itaconic anhydride also is apreferred reagent to provide anhydride polymer units, preferably wherethe itaconic anhydride has purified such as by extraction withchloroform prior to polymerization. Vinyl lactones are also preferredreagents, such as alpha-butyrolactone.

[0046] Some suitable vinyl (endocyclic double bond) heterocyclicmonomers that can be polymerized to provide polymers of the inventioninclude the following:

[0047] Preferably a polymer of the invention will have a weight averagemolecular weight (Mw) of about 800 or 1,000 to about 100,000, morepreferably about 2,000 to about 30,000, still more preferably from about2,000 to 15,000 or 20,000, with a molecular weight distribution (Mw/Mn)of about 3 or less, more preferably a molecular weight distribution ofabout 2 or less. Molecular weights (either Mw or Mn) of the polymers ofthe invention are suitably determined by gel permeation chromatography.

[0048] Polymers of the invention used in photoresist formulations shouldcontain a sufficient amount of photogenerated acid labile ester groupsto enable formation of resist relief images as desired. For instance,suitable amount of such acid labile ester groups will be at least 1 molepercent of total units of the polymer, more preferably about 2 to 50mole percent, still more typically about 3 to 30 or 40 mole percent oftotal polymer units. See the examples which follow for exemplarypreferred polymers.

[0049] As discussed above, the polymers of the invention are highlyuseful as a resin binder component in photoresist compositions,particularly chemically-amplified positive resists. Photoresists of theinvention in general comprise a photoactive component and a resin bindercomponent that comprises a polymer as described above.

[0050] The resin binder component should be used in an amount sufficientto render a coating layer of the resist developable with an aqueousalkaline developer.

[0051] The resist compositions of the invention also comprise aphotoacid generator (i.e. “PAG”) that is suitably employed in an amountsufficient to generate a latent image in a coating layer of the resistupon exposure to activating radiation. Preferred PAGs for imaging at 193nm and 248 nm imaging include imidosulfonates such as compounds of thefollowing formula:

[0052] wherein R is camphor, adamantane, alkyl (e.g. C₁₋₁₂ alkyl) andperfluoroalkyl such as perfluoro(C₁₋₁₂alkyl), particularlyperfluorooctanesulfonate, perfluorononanesulfonate and the like. Aspecifically preferred PAG isN-[(perfluorooctanesulfonyl)oxy]-5-norbornene-2,3-dicarboximide.

[0053] Sulfonate compounds are also suitable PAGs, particularlysulfonate salts. Two suitable agents for 193 nm and 248 nm imaging arethe following PAGS 1 and 2:

[0054] Such sulfonate compounds can be prepared as disclosed in EuropeanPatent Application 96118111.2 (publication number 0783136), whichdetails the synthesis of above PAG 1.

[0055] Also suitable are the above two iodonium compounds complexed withanions other than the above-depicted camphorsulfonate groups. Inparticular, preferred anions include those of the formula RSO₃— where Ris adamantane, alkyl (e.g. C₁₋₁₂ alkyl) and perfluoroalkyl such asperfluoro (C₁₋₁₂alkyl), particularly perfluorooctanesulfonate,perfluorobutanesulfonate and the like.

[0056] Other known PAGS also may be employed in the resists of theinvention. Particularly for 193 nm imaging, generally preferred are PAGSthat do not contain aromatic groups, such as the above-mentionedimidosulfonates, in order to provide enhanced transparency.

[0057] A preferred optional additive of resists of the invention is anadded base, particularly tetrabutylammonium hydroxide (TBAH), ortetrabutylammonium lactate, which can enhance resolution of a developedresist relief image. For resists imaged at 193 nm, a preferred addedbase is a hindered amine such as diazabicyclo undecene ordiazabicyclononene. The added base is suitably used in relatively smallamounts, e.g. about 0.03 to 5 percent by weight relative to the totalsolids.

[0058] Photoresists of the invention also may contain other optionalmaterials. For example, other optional additives include anti-striationagents, plasticizers, speed enhancers, etc. Such optional additivestypically will be present in minor concentrations in a photoresistcomposition except for fillers and dyes which may be present inrelatively large concentrations, e.g., in amounts of from about 5 to 30percent by weight of the total weight of a resist's dry components.

[0059] The resists of the invention can be readily prepared by thoseskilled in the art. For example, a photoresist composition of theinvention can be prepared by dissolving the components of thephotoresist in a suitable solvent such as, for example, ethyl lactate,ethylene glycol monomethyl ether, ethylene glycol monomethyl etheracetate, propylene glycol monomethyl ether; propylene glycol monomethylether acetate and 3-ethoxyethyl propionate. Typically, the solidscontent of the composition varies between about 5 and 35 percent byweight of the total weight of the photoresist composition. The resinbinder and photoactive components should be present in amountssufficient to provide a film coating layer and formation of good qualitylatent and relief images. See the examples which follow for exemplarypreferred amounts of resist components.

[0060] The compositions of the invention are used in accordance withgenerally known procedures. The liquid coating compositions of theinvention are applied to a substrate such as by spinning, dipping,roller coating or other conventional coating technique. When spincoating, the solids content of the coating solution can be adjusted toprovide a desired film thickness based upon the specific spinningequipment utilized, the viscosity of the solution, the speed of thespinner and the amount of time allowed for spinning.

[0061] The resist compositions of the invention are suitably applied tosubstrates conventionally used in processes involving coating withphotoresists. For example, the composition may be applied over siliconwafers or silicon wafers coated with silicon dioxide for the productionof microprocessors and other integrated circuit components.Aluminum-aluminum oxide, gallium arsenide, ceramic, quartz, copper,glass substrates and the like are also suitably employed.

[0062] Following coating of the photoresist onto a surface, it is driedby heating to remove the solvent until preferably the photoresistcoating is tack free. Thereafter, it is imaged through a mask inconventional manner. The exposure is sufficient to effectively activatethe photoactive component of the photoresist system to produce apatterned image in the resist coating layer and, more specifically, theexposure energy typically ranges from about 1 to 100 mJ/cm², dependentupon the exposure tool and the components of the photoresistcomposition.

[0063] As discussed above, coating layers of the resist compositions ofthe invention are preferably photoactivated by a short exposurewavelength, particularly a sub-300 and sub-200 nm exposure wavelength.As discussed above, 193 nm is a particularly preferred exposurewavelength. 157 nm also is a preferred exposure wavelength. However, theresist compositions of the invention also may be suitably imaged athigher wavelengths. For example, a resin of the invention can beformulated with an appropriate PAG and sensitizer if needed and imagedat higher wavelengths e.g. 248 nm or 365 nm.

[0064] Following exposure, the film layer of the composition ispreferably baked at temperatures ranging from about 70° C. to about 160°C. Thereafter, the film is developed. The exposed resist film isrendered positive working by employing a polar developer, preferably anaqueous based developer such as quaternary ammonium hydroxide solutionssuch as a tetra-alkyl ammonium hydroxide solution; various aminesolutions preferably a 0.26 N tetramethylammonium hydroxide, such asethyl amine, n-propyl amine, diethyl amine, di-n-propyl amine, triethylamine, or methyldiethyl amine; alcohol amines such as diethanol amine ortriethanol amine; cyclic amines such as pyrrole, pyridine, etc. Ingeneral, development is in accordance with procedures recognized in theart.

[0065] Following development of the photoresist coating over thesubstrate, the developed substrate may be selectively processed on thoseareas bared of resist, for example by chemically etching or platingsubstrate areas bared of resist in accordance with procedures known inthe art. For the manufacture of microelectronic substrates, e.g., themanufacture of silicon dioxide wafers, suitable etchants include a gasetchant, e.g. a halogen plasma etchant such as a chlorine orfluorine-based etchant such a Cl₂ or CF₄/CHF₃ etchant applied as aplasma stream. After such processing, resist may be removed from theprocessed substrate using known stripping procedures.

[0066] All documents mentioned herein are incorporated herein byreference. The following non-limiting examples are illustrative of theinvention.

EXAMPLE 1 Synthesis of Polymer Containing Vinylene Carbonate

[0067]

[0068] Polymer of the above structure (units in the following molaramount as appearing from left to right: 20/10/30/40) was synthesized asfollows.

[0069] A mixture of 2-methyladamantanyl methacrylate (15.64 g), maleicanhydride (4.91 g), norbomene (1.57 g), vinylene carbonate (2.87 g), anddimethyl-2,2′-azodiisobutyrate (0.77 g, 2 mol % of total monomers) in 25g of dioxane was placed in a round-bottomed flask fitted with a refluxcondenser and nitrogen purge. The flask was then placed in a pre-heated85° C. oil bath. This reaction mixture was stirred at this temperaturefor 24 hours, under nitrogen. After cooling the reaction mixture to roomtemperature, the solution was diluted to 33% (wt/wt) with dioxane. Thepolymer was isolated by precipitation into 1 L of isopropyl alcohol,then filtered off and washed with an additional 100 ml of isopropylalcohol. Finally, the polymer was dried in a vacuum oven at 40° C. forovernight, yield=60%.

EXAMPLE 2 Synthesis of Polymer Containing 4,7-Dihydro-1,3 Dioxepin

[0070]

[0071] A polymer of the above structure (units in the following molaramount as appearing from left to right: 20/10/30/40) was synthesized asfollows.

[0072] A mixture of 2-methyladamantanyl methacrylate (15.35 g), maleicanhydride (4.82 g), norbomene (1.54 g), 4,7-dihydro -1,3 dioxepin (3.28g), and dimethyl-2,2′-azodiisobutyrate (0.76 g, 2 mol %/of totalmonomers) in 25 g of dioxane was placed in a round-bottomed flask fittedwith a reflux condenser and nitrogen purge. The flask was then placed ina pre-heated 85° C. oil bath. This reaction mixture was stirred at thistemperature for 24 hours, under nitrogen. After cooling the reactionmixture to room temperature, the solution was diluted to 33% (wt/wt)with dioxane. The polymer was isolated by precipitation into 1 L ofisopropyl alcohol, then filtered off and washed with an additional 100ml of isopropyl alcohol. Finally, the polymer was dried in a vacuum ovenat 40° C. for overnight, yield=62%.

EXAMPLE 3 Photoresist Preparation and Lithographic Processing

[0073] A photoresist of the invention is prepared by mixing thefollowing components with amount expressed as weight percents based ontotal weight of the resist composition: Resist components Amount (wt. %based on total solids) Resin binder 28.2 Photoacid generator 0.52 Basicadditive 0.03 Surfactant 0.03

[0074] The resin binder is the polymer of Example 2 above. The photoacidgenerator is triphenylsulfonium triflate. The basic additive istriisopropanol amine. The surfactant is Silwet (Dow Chemical). Thoseresist components were formulated at 16 wt. % solids in a solvent of2-heptatone.

[0075] The formulated resist composition is spin coated onto HMDS vaporprimed 4 inch silicon wafers and softbaked via a vacuum hotplate at 130°C. for 60 seconds. The resist coating layer is exposed through aphotomask at 193 nm using an ISI microstepper, and then the exposedcoating layers are post-exposure baked (PEB) at about 130° C. The coatedwafers are then treated with alkaline aqueous developer (0.26N aqueoustetramethylammonium hydroxide solution to develop the imaged resistlayer and provide a relief image.

EXAMPLES 4-7 Syntheses of Monomers Useful in Preparation of Polymers ofthe Invention EXAMPLE 4 EtTCD Methacrylate Monomer Synthesis

[0076] 8-ethyl-8-tricyclodecanylmethacrylate (EtTCD methacrylate) wasprepared as following using the reagents and amounts thereof asspecified in the following table. Material Amt (g) Amt (ml) Moles SourceTCD 150.22 ′1.00 TCI Ethylmagnesiumchloride (25%) 390.85 ˜379.5 ˜1.10ACROS Methacryloyl chloride 120.22 ˜112.4 ˜1.15 Aldrich Tetrahydrofuran480 540 Aldrich

[0077] All reaction glassware was dried in the oven overnight at 100° C.The glassware was set up and cooled under a stream of nitrogen. Thereaction was carried out under a blanket of nitrogen.

[0078] To a 2L 3N-RB flask fitted with a gas inlet, thermometer,overhead stirrer and a rubber septum was added 400 g of ethylmagnesiumchloride, 25 wt % solution in tetrahydrofuran (clear, amber solution)via a double tipped needle using nitrogen pressure. The mixture wascooled to −25 to −30° C. using a dry ice/isopropanol bath. While theethylmagnesium chloride solution was cooling the 153.6 g oftricyclodecane (TCD) was dissolved in 480 g of tetrahydrofuran. To a 1L3N-RB flask equipped with a gas inlet, glass stopper and a rubber septumwas added the 153.6 g of TCD. The anhydrous, inhibitor freetetrahydrofuran was transferred to the 1L flask via a double tippedneedle using nitrogen pressure. When the ethylmagnesium chloride was at−25 to −30° C., the TCD/THF solution was transferred over a 2 hr periodto the 2L 3N-RB flask containing the ethylmagnesium chloride via adouble tipped needle using nitrogen pressure. The cooling bath wasremoved and the reaction mixture was sired for 2 hr. After stirring for2 hr the mixture was again cooled to −25 to −30° C. using a dryice/isopropanol bath. The methacryloyl chloride (120.22 g) was thenadded dropwise over a 1 hour period using a 125 ml pressure equalizingdropping funnel. The reaction was allowed to come to room temperaturewith overnight stirring. A white precipitate developed from the clearamber colored reaction solution. Water (DI) was added until all of thesalts had dissolved (˜500 ml) and two distinct layer were seen. Thelayers were separated and the organic (upper) layer was washed with2×400 ml DI water then dried over magnesium sulfate. The THF was removedleaving 258 g of an orange oil. The orange oil was dissolved in 400 g ofhexane then passed through a 400 g silica gel plug which had beenpre-conditioned with hexane. The silica was washed with hexane until allof the product was removed (spot filtrate on a TLC plate and illuminateunder short UV). The hexane was removed leaving 202.8 g of an clear,colorless oil. Theoretical yield: 248.4 g; yield: 81.6%

EXAMPLE 5 Synthesis of Norbomene Valerolactone

[0079] A solution of valerolactone (50.1 g) in 150 mL of anhydrous THFwas placed in a three-neck-bottomed flask at −78° C. (Dry Ice/acetone).To it, solution of LDA (250 mL, 2M) in 250 mL anhydrous THF was addeddropwise. The reaction mixture was stirred at this temperature for 4hours. Then, the thermal cracking of paraformaldehyde (36.94 g, excess)was bubbled into the reaction mixture. After the paraformaldehyde wasall cracked, the reaction mixture was stirred at the same bath andstirred for overnight. Then, the solvent was removed by rotary pump andthe residue was added 500 mL CH₂Cl₂ and washed with NaHCO₃ (aq, sat.)and water several times (3×500 mL). The combination organic solvent wasdried over MgSO₄ and the solvent was removed by rotary pump. The desiredproduct was distilled under vacuum (135-140° C./8 mmHg)

[0080] The methylene-valerolactone was dissolved in dichloromethane andfreshly cracked cyclopentadiene was added. The reaction mixture wasstirred at room temperature for 3 hours, then heated to 40° C., and heldat 40° C. overnight. The reaction mixture was then slowly cooled to roomtemperature. The methylene chloride was removed under reduced pressure,leaving an oil. The crude oil was then distilled under reduced pressureto afford pure product.

EXAMPLE 6 Synthesis of 8-Methyltricyclodecanyl Methacrylate

[0081]

[0082] A solution of 125 ml of 1.4 M methyl lithium (in ethyl ether)in100 ml of hexane was decanted into a three neck round-bottom flask at anice-water bath. To it, a solution of 24.00 g oftricyclo[5.2.1.0]decan-8-one in hexane was added dropwise. Afteraddition, the reaction mixture was stirred for 4 hours at 0° C. Then, asolution of 16 ml of methacroyl chloride in 100 ml of hexane was addeddropwise at 0° C. After. addition, the reaction mixture was stirred atthe same bath for overnight (16 hours). After filtering the white salts,the organic layer was washed with water three times (3×300 ml). Then,the washed organic layer was dried over anhydrous MgSO₄. The organicsolvent was removed by a rotary pump to give the crude title monomer(23.5 g). The monomer was purified by a flash column chromatography(purity >98%, silica gel with hexane). ¹H NMR: 6.05 (1H), 5.50 (1H),1.95 (3H), 1.65 (3H), 2.25-0.85 (14H).

EXAMPLE 7 Synthesis of Pinanyl Methacrylate

[0083]

[0084] Materials Used: Amount Charged Moles Source cis-Pinan-2-ol 15.43g 0.10 Fluka Et₃N 12.14 g 0.12 Aldrich, distilled before useMethacryloyl chloride 13.07 g 0.125 Aldrich, distilled before use CH₂Cl₂230 mL Aldrich, dried and distilled

[0085] Procedure:

[0086] All reaction glassware and needles were dried and flushed withdry N₂ before use and the reaction was carried out under nitrogenatmosphere.

[0087] 1) Into a 500 mL 3-neck round-bottom-flask equipped with anaddition funnel and a magnetic stirrer were added 15.43 g ofcis-pinan-2-ol and 200 mL of dry CH₂Cl₂ (Stirred over CaH₂ overnight,then distilled and stored over activated molecular sieves). Theresulting colorless solution was cooled with an ice-water bath.

[0088] 2) Triethylamine (12.14 g) was added through the addition funnelto the cooled CH₂Cl₂. solution over 10 min. After added, the resultingsolution was kept in a dry-ice/acetone bath (−67° C.).

[0089] 3) A CH₂Cl₂ (30 mL) solution of methacryloyl chloride (13.07 g)was added dropwisely over 20 min. The resulting orangish suspension wasallowed to warm to room temperature and stirred for 2 h.

[0090] 4) The chloride salts were filtered off. The filtrate was washedwith saturated Na₂CO₃ solution (2×200 mL), then DI water (3×200 mL), anddried over anhydrous MgSO₄.

[0091] 5) The slightly yellow CH₂C₁₂ solution was concentrated on arotary evaporator (bath temperature kept below 35°) to yield a clearslightly yellow liquid product. Yield=79%. The product was judged pureby NMR.

[0092] The foregoing description of the invention is merely illustrativethereof, and it is understood that variations and modification can bemade without departing from the spirit or scope of the invention as setforth in the following claims.

What is claimed is:
 1. A photoresist composition comprising aphotoactive component and a polymer that comprises a unit selected fromthe group of i) a carbonate unit, and ii) a lactone provided by amonomer having a ring oxygen adjacent to a vinyl group.
 2. A photoresistcomposition of claim 1 wherein the carbonate unit and/or lactone arefused to the polymer backbone.
 3. A photoresist composition of claim 1or 2 wherein the polymer comprises photoacid-labile groups.
 4. Aphotoresist composition of any one of claims 1 through 3 wherein polymerfurther comprises a carbon alicyclic group fused to the polymerbackbone.
 5. The photoresist composition of claim 4 wherein the carbonalicyclic group is a polymerized norbornene group.
 6. The photoresistcomposition of claim 4 or 5 wherein the carbon alicyclic group comprisesa photoacid-labile group.4
 7. A photoresist composition of any one ofclaims 1 through 6 wherein the polymer comprises a heteroalicyclic groupin addition to the carbonate or lactone.
 8. A photoresist composition ofclaim 7 wherein the additional heteroalicyclic group comprises an oxygenring member and/or a sulfur ring member.
 9. The photoresist compositionof claim 7 or 8 wherein the additional heteroalicyclic group has anon-hydrogen ring substituent.
 10. The photoresist composition of anyone of claims 1 through 9 wherein the polymer comprises aphotoacid-labile group that is a substituent of an additionalheteroalicyclic polymer group or a carbon alicyclic polymer group. 11.The photoresist composition of any one of claims 1 through 10 whereinthe polymer comprises a photoacid-labile moiety of a polymer unitseparate a carbonate, lactone or carbon alicyclic unit.
 12. Thephotoresist composition of any one of claims 1 through 11 wherein thepolymer comprises a polymerized acrylate that comprises aphotoacid-labile moiety.
 13. The photoresist composition of any one ofclaims 1 through 12 wherein the polymer further comprises anhydrideunits.
 14. The photoresist composition of any one of claims 1 through 13wherein the polymer further comprises maleic anhydride units.
 15. Thephotoresist composition of any one of claims 1 through 14 wherein thepolymer is a terpolymer.
 16. The photoresist composition of any one ofclaims 1 through 14 wherein the polymer is a tetrapolymer or apentapolymer.
 17. The photoresist composition of any one of claims 1through 16 wherein the polymer is substantially free of aromatic groups.18. The photoresist composition of any one of claims 1 through 17wherein the photoactive component comprises one or more photoacidgenerator compounds.
 19. The photoresist composition of any one ofclaims 1 through 18 wherein the photoresist is a chemically-amplifiedpositive-acting resist.
 20. A method of forming a positive photoresistrelief image, comprising: (a) applying a coating layer of a photoresistof any one of claims 1 though 19 on a substrate; and (b) exposing anddeveloping the photoresist layer to yield a relief image.
 21. The methodof claim 20 wherein the photoresist layer is exposed with radiationhaving a wavelength of less than about 200 nm.
 22. The method of claim20 wherein the photoresist layer is exposed with radiation having awavelength of about 193 nm. 23 The method of claim 20 wherein thephotoresist layer is exposed with radiation having a wavelength of about157 nm.
 24. An article of manufacture comprising a microelectronic wafersubstrate or flat panel display substrate having coated thereon a layerof the photoresist composition of any one of claims 1 though
 19. 25. Apolymer that comprises a unit selected from the group of i) a carbonateunit, and ii) a lactone provided by a monomer having a ring oxygenadjacent to a vinyl group.
 26. A polymer of claims 25 wherein thecarbonate unit and/or lactone are fused to the polymer backbone.
 27. Apolymer of claim 25 or 26 wherein the polymer comprises photoacid-labilegroups.
 28. A polymer of any one of claims 25 through 27 wherein polymerfurther comprises a carbon alicyclic group fused to the polymerbackbone.
 29. A polymer of any one of claims 25 through 28 wherein thecarbon alicyclic group is a polymerized norbomene group.
 30. A polymerof claim 28 or 29 wherein the carbon alicyclic group comprises aphotoacid-labile group.4
 31. A polymer of any one of claims 25 through30 wherein the polymer comprises a heteroalicyclic group in addition tothe carbonate or lactone.
 32. A polymer of any one of claims 25 through31 wherein the additional heteroalicyclic group comprises an oxygen ringmember and/or a sulfur ring member.
 33. A polymer of any one of claims25 through 32 wherein the additional heteroalicyclic group has anon-hydrogen ring substituent.
 34. A polymer of any one of claims 25through 33 wherein the polymer comprises a photoacid-labile group thatis a substituent of an additional heteroalicyclic polymer group or acarbon alicyclic polymer group.
 35. A polymer of any one of claims 25through 34 wherein the polymer comprises a photoacid-labile moiety of apolymer unit separate a carbonate, lactone or carbon alicyclic unit. 36.A polymer of any one of claims 25 through 35 wherein the polymercomprises a polymerized acrylate that comprises a photoacid-labilemoiety.
 37. A polymer of any one of claims 25 through 36 wherein thepolymer further comprises anhydride units.
 38. A polymer of any one ofclaims 25 through 37 wherein the polymer further comprises maleicanhydride units.
 39. A polymer of any one of claims 25 through 38wherein the polymer is a terpolymer.
 40. A polymer of any one of claims1 through 14 wherein the polymer is a tetrapolymer or a pentapolymer.